Eggdrop is a standalone application.
It runs as an automated IRC client sitting in channel(s) on an IRC server.
It, if correctly configure, keeps order in a channel when there's no humans around. Enforces bans, prevents flooding, etc.
Where it resides is entirely up to you, but I wouldn't put it in a directory accessible from the web - it wouldn't be difficult to grab your eggdrop user file and brute-force the passwords (and seeing all the hostmasks for users in the file would also give a potential attacker clues on where to hunt for proxies to spoof & pose as a legitimate bot user).
You can get it from
www.egghelp.org.